I could be wrong about this most say the other way towards the face. True mechs are not polarity dependent, but there may be issues with contacts. The 510 is smaller, so it is more likely to just contact the positive while the button contact tends to be larger and if a wrap and ring are damaged it might be more inclined to make contact to positive and negative.Mech tubes, the positive should be facing the button, away from the face towards the vent holes.